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+// Calculating the temperature rise and thermal time constant and rating of the machine

+clc;

+disp('Example 4.15, Page No. = 4.23')

+// Given Data

+D = 0.6;// Diameter of induction motor (in meter)

+L = 0.9;// Length of induction motor (in meter)

+out = 7500;// Output of induction motor (in W)

+e = 0.9;// Efficiency

+G = 375;// Weight of material (in kg)

+h = 725;// Specific heat (in J/kg degree celsius)

+Lem = 12;// Specific heat dissipation (in Watt per meter square degree celsius)

+// Calculation of the temperature rise and thermal time constant of the machine

+S = (%pi*D*L)+(2*%pi/4*D^(2));// Total heat dissipating surface (in meter square)

+Q = (out/e)-out;// Losses (in Watts)

+Tm = Q/(S*Lem);// Final temperature rise (in degree celsius)

+Th = G*h/(S*Lem);// Time constant (in seconds)

+disp(Tm,'(a) Final temperature rise (degree celsius) =');

+disp(Th,'    Time constant (seconds) =');

+// Calculation of the rating of the machine

+Lem_new = 25;// Specific heat dissipation (in Watt per meter square degree celsius)

+Q = Tm*S*Lem_new;// Losses (in Watts)

+out = (e*Q)/(1-e);// Output of induction motor (in W)

+disp(out,'(b) Rating of the machine (Watt) =');

+//in book answers are 30.85 degree celsius, 10025 seconds and 15687 watts.  The answers vary due to round off error

+